Surgical cannulas have been used for many years to perform a variety of surgical procedures, such as liposuction.
To perform liposuction, for example, a hand-held instrument (known as a cannula) is inserted through a portal or incision in the patient's skin and into pockets of fat located between the patient's skin and muscles. Once inserted below the skin and into the fat pockets, the cannula is moved around by the surgeon to break up the fat cells. Parcels of the fat tissue are then aspirated through small openings along the sides of the cannula by vacuum applied by a syringe or a pump. The fat tissue is drawn through a central bore, known as a lumen, in the cannula, to a tissue canister connected in fluid communication between the cannula and the suction source.
A typical cannula, of the type used for liposuction, for example, includes an elongated tubular shaft, closed by a cannula tip at the distal end of the shaft which is inserted through the patient's skin. The aspirator tip, and shaft, may include small openings along the sides or at the end of the tip, to create a passage for movement of the tissue to be removed into the central bore of the cannula. The end of the tubular shaft opposite from the cannula tip is typically equipped with a surgical handle to be grasped by the surgeon or a fitting for connecting the cannula to a syringe or other vacuum source. The end of the cannula having the handle or fitting may also be configured for attachment to an infiltration syringe or other source of infiltration fluid.
During use, the vacuum created by suction within the bore of the cannula causes tissue to be pulled into the openings along the sides and at the aspirator tip of the cannula. In some procedures, a cannula of the type described hereinabove may also be used for injecting a fluid into the tissue, in a procedure known as infiltration or tumescent infiltration.
In use, therefore, a typical surgical cannula performs one or more of three basic functions. First, the cannula is used to penetrate, crush, tear, or avulse the fatty tissue in such a manner that it can be suctioned through the openings into the central bore of the cannula. Secondly, the cannula may be used to suction fatty tissue through the central bore to aspirate tissue fragments and fluids from the operative site. Thirdly, the cannula may be used for infiltrating the operative site with a fluid to facilitate breaking up and removing the fatty tissue. It is desirable to provide an improved cannula and method of use for a cannula which enhances the performance of any of these basic functions of the cannula. It is also desirable to provide an improved cannula which is safer for the patient, and which reduces fatigue on the surgeon performing a procedure utilizing the cannula.
It is specifically desirable to provide an improved cannula and method for use having an improved ability to effectively remove, crush, tear or avulse fatty tissue at the operative site. It has been noted that, during aspiration of fatty tissue and fluids from the surgical site, a seal can be created between the outer surface of prior cannulas and the fatty tissue which inhibits the flow of any ambient pressure fluid, such as air, to the operative site about the tip of the cannula. When suction is applied, such a seal prevents the flow of any ambient pressure fluid to the operative site about the shaft or tip of the cannula. When this occurs, the suction capacity of the cannula is substantially reduced, and the fatty tissue fragments and fluids move more slowly than is desirable through the cannula and any related suction equipment to the tissue canister.
Another area in which improvement is desirable, is the cost of such surgical cannulas. Primarily as a cost-saving measure, prior surgical cannulas are typically reused for multiple patients, with the cannulas being subjected to sterilization by steam, or other methods between uses. Although such sterilization has generally been sufficient to protect the subsequent patients, it is well-known that, due to the construction of a typical cannula, small tissue fragments may remain inside the cannula. It has also been prior practice in reusing cannulas to subject the cannulas to enzymatic cleaning agents, germicides, disinfectants, and other cleaning agents, which may also be partly retained inside the cannula. These residual tissue particles and/or chemical agents potentially subject the subsequent patient to an increased risk of complications during, or following a surgical procedure. It is highly desirable, therefore, to provide a surgical cannula and method which does not require or rely upon reuse of the cannulas.
It is also desirable that an improved cannula be configured and adapted for interchangeable use with commonly available suction and tissue removal, or aspiration equipment.
It is also desirable that an improved cannula be configured and adapted for interchangeable use with commonly available infiltration equipment.